Methods of producing 9-oxo-9-phosphafluorene-based chemicals are known in the art. However, a polymer that contains in the backbone a 9-oxo-9-phosphafluorene-2,7-diyl skeleton or a combination of the skeleton and a vinylene or arylene skeleton, and a process for producing it, as well as the behavior of the polymer for a component of a luminescent element or electrochromic element are unknown. In addition, 2,7-dihalo-9-alkyl-9-oxo-9-phosphafluorene compounds that are used as the starting monomer for the polymer, and a process for producing them are also unknown.